Metering pump

ABSTRACT

A pump has a reservoir containing a supply of driving fluid. Mounted within the reservoir is a drive mechanism for reciprocating a piston within a cylinder. The drive mechanism has an eccentrically mounted member which is slidably surrounded by a sliding block, the latter being enclosed by a cross-head which is connected to the piston and confined so as to reciprocate within the pump. Thus, rotary motion is converted to oscillating motion in the sliding block, and the oscillating motion is then converted to reciprocating motion in the cross-head, the reciprocating motion then being transmitted to the piston. Two elastomeric tubes have their ends mounted within the pump so as to permit distortion (expansion or compression) of the central portions of the tubes. In the preferred embodiment of the invention, a displacement chamber is defined between the piston and the inner surface of the first tube, and an intermediate chamber is defined between the outer surfaces of the tubes, the intermediate chamber containing an intermediate driving fluid. As the piston reciprocates, driving fluid alternately passes into and out of the displacement chamber to cause the first tube to alternate between a first configuration, and a second configuration, which in turn causes the second tube to do likewise via the intermediate driving fluid. As a result of the alternating configurations assumed by the second tube, process fluid is pumped through the second tube. Other modifications are also disclosed.

United States Patent Flynn et al.

Oct. 7, 1975 METERING PUMP [75] Inventors: Jac B. Flynn, Elgin; Werner K.

Priese, Barrington, both of 111.

[73] Assignee: Valve Systems International, Inc.,

Bala Cynwyd, Pa.

[22] Filed: Mar. 18, 1974 [2]] Appl. No.: 451,748

Related U.S. Application Data [62] Division-of Ser. No. 288,532, Sept. 13, 1972, Pat.

[52] U.S. Cl 417/387; 417/499 [51] Int. Cl. F04B 9/08 [58] Field of Search 417/383389, 417/494, 499

[56] References Cited UNITED STATES PATENTS 2,394,371 2/1946 Davis 417/387 2,571,312 10/1951 Trevaskis 417/499 2,821,926 2/1958 Miller et a1. 417/499 2,827,853 3/1958 Bradley 417/389 2,960,936 11/1960 Dean et a1. 417/387 3,149,469 9/1964 Williams 417/387 3,179,061 4/1965 Budzich 417/499 3,354,831 11/1967 Acker 417/387 FOREIGN PATENTS OR APPLICATIONS 7/1953 France 417/383 Primary ExaminerWilliam L. Freeh Assistant Examiner-G. P. La Pointe Attorney, Agent, or FirmOlsen, Trexler, Wolters, Bushnell & Fosse, Ltd.

[ 57] ABSTRACT A pump has a reservoir containing a supply of driving fluid. Mounted within the reservoir is a drive mechanism for reciprocating a piston within a cylinder. The drive mechanism has an eccentrically mounted member which is slidably surrounded by a sliding block, the latter being enclosed by a cross-head which is connected to the piston and confined so as to reciprocate within the pump. Thus, rotary motion is converted to oscillating motion in the sliding block, and the oscillating motion is then converted to reciprocating motion in the cross-head, the reciprocating motion then being transmitted to the piston. Two elastomeric tubes have their ends mounted within the pump so as to permit distortion (expansion or compression) of the central portions of the tubes. In the preferred embodiment of the invention, a displacement chamber is defined between the piston and the inner surface of the first tube, and an intermediate chamber is defined between the outer surfaces of the tubes, the intermediate chamber containing an intermediate driving fluid. As the piston reciprocates, driving fluid alternately passes into and out of the displacement chamber to cause the first tube to alternate between a first configuration, and a second configuration, which in turn causes the second tube to do likewise via the intermediate driving fluid. As a result of the alternating configurations assumed by the second tube, process fluid is pumped through the second tube. Other modifications are also disclosed.

4 Claims, 15 Drawing Figures 5 g 13:1] i /L 64 54 I I YI v I i 1. 63 AVA a 444 36 l, l 7 i1 g i n 56 1 I i I a? da J 52 i e2 75 61 1 I 40 l J? 43 I] 1 V LLD US. Patent Oct. 7,1975 Sheet 1 of7 3,910,727

Sheet 2 of 7 3,910,727

US. Patent Oct. 7,1975

U.S. Patent Oct. 7,1975 Sheet4 0f7 3,910,727

Sheet 5 0f 7 M \ww y/m wi WI US. Patent Oct. 7,1975

US. Patent Oct. 7,1975 Sheet6 0f7 3,910,727

US. Patent Oct. 7,1975 Sheet 7 of7 3,910,727

METERING PUMP REFERENCE TO RELATED APPLICATION This application is a division of US. application Ser. No. 288,532, filed Sept, 13, 1972, now US. Pat. No. 3,816,032.

BACKGROUND OF THE INVENTION Various types of metering pumps are presently in use. Some utilize a single diaphragm in combination with a piston and cylinder, while others utilize a double diaphragm. In both types, a displacement and a pumping chamber is partially defined by a diaphragm within the pump. In the double diagraphm type, however, an intermediate chamber is also defined between the process diaphragm and the hydraulic diaphragm, the intermediate chamber giving additional protection in the event of diaphragm failure. The intermediate chamber contains a liquid which is compatible with the process fluid being pumped. Thus, the process fluid is not contaminated in the event of diaphragm failure. All diaphragm type pumps, however, have the same disadvantage. Because the process fluids being pumped are often corrosive, the diaphragms per se are often made of noble metals for their corrosion resistance. The diaphragm heads on these pumps require a pressure vessel flange which is exposed to the process fluid. Consequently, this part of the pump housing must be manufactured from exotic metals which are also resistant to corrosion. As a result, the diaphragm heads are large, heavy, and expensive.

In some instances, the diaphragm head may be manufactured from plastics which are resistant to corrosion rather than exotic metal. In contrast to the metal diaphragm heads, however, plastic diaphragm heads are limited to low pressure applications.

Other metering pumps utilize a single elastomeric tube to partially define a pumping chamber and a displacement chamber; and ultimately effect the pumping of process fluid through the pumping chamber. In these pumps, if the tube ruptures during the operation of the pump, the displacement chamber will be damaged if the process fluid being pumped is corrosive. In any event, the process fluid will be contaminated by oil.

Another type of pump utilizes a single elastomeric tube in combination with a diaphragm, there being an intermediate chamber between the diaphragm and the outer surface of the tube. Thus, by using a fluid in the intermediate chamber which is compatible with the process fluid being pumped, contamination of the process fluid can be prevented in the event of tube failure. With this construction and that described in the previous paragraph. however, there is nothing to restrain or limit the movement of the tube beyond its elastic limit in the event there is an abnormal occurrence. Thus, in either construction, the tube is still likely to rupture given an abnormal occurrence. Furthermore, this type of pump construction is subject to the disadvantages inherent with the use of diaphragms.

Another problem encountered with present metering pumps relates to the drive mechanism for converting the rotary motion of an electric motor to reciprocating motion. In many pumps, as it became necessary to bandle higher horesepower transmissions, more complex drive mechanisms were developed. The complex drive mechanisms developed are consequently more likely to malfunction; also, larger pump housings are required to accommodate the more complex drive mechanisms,

Examples of pumps which incorporate flexible diaphragms and tubes are shown in US. Pat. Nos. 1,282,145; 2,345,693; 2,812,716; 3,250,226; 3,318,251; 3,489,096; 3,527,550; and 3,551,076.

SUMMARY OF THE INVENTION The present invention relates to an improved metering pump and pumping head. The pump includes an improved drive mechanism for reciprocating a piston within a cylinder. The pumping head employs, two elastomeric tubes, a hydraulic tube and a process tube, each have their ends secured within the pump housing so as to permit distortion of the central portion of each tube by a driving fluid. In the preferred embodiment of the invention, a displacement chamber is defined between the piston and the inner surface of the hydraulic tube for confining a volume of driving fluid during the reciprocation of the piston. During the reciprocation of the piston, passageways between the piston and cylinder periodically communicate with a reservoir containing a supply of the driving fluid to allow driving fluid to enter and exit the displacement chamber.

During the discharge stroke of the piston, driving fluid confined Within the displacement chamber is displaced and causes the hydraulic tube to expand. As the hydraulic tube expands, it causes displacement of an intermediate driving fluid which is confined within an intermediate chamber, the latter being partially defined by the outer surface of each of the tubes. Consequently, displacement of the intermediate fluid com presses the process tube, causing process fluid contained within a pumping chamber within the tube to be discharged around an outlet valve.

During the suction stroke of the piston, each tube returns to its original position, causing process fluid to enter the pumping chamber around an inlet valve. On the next discharge stroke of the piston, the process will be repeated, and the process fluid which has entered the pumping chamber, will be discharged around the outlet valve once again.

The cylinder includes an adjustably mounted sleeve, the position of which can be changed with respect to the piston so as to vary the degree to which the passageways between the piston and the sleeve communicate with the reservoir during the reciprocation of the piston.

The drive mechanism for reciprocating the piston includes a first member having a circular cross-section which is eccentrically mounted so as to rotate about an axis normal to the cross-section. The cross-section of the first member is surrounded by a sliding block, the block in turn being enclosed by a crosshead which is confined so as to reciprocate within the pump housing. As the first member rotates, it causes the block to oscillate, which in turn causes the crosshead to reciprocate within the pump housing. The crosshead is connected to the piston, thus causing the latter to reciprocate.

Perforated sleeves define limit surfaces which surround both tubes, and in addition a perforated sleeve is mounted within the hydraulic tube to stop the tube in its original position during the suction stroke of the piston.

A second embodiment of the pumping head of the present invention is disclosed in which the elastomeric tubes are concentrically arranged; perforated sleeves define limit surfaces on each side of the hydraulic tube, and a limit surface surrounds the process tube. Various modifications are disclosed for both embodiments which include different sleeve arrangements.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of the preferred embodiment of the invention taken through line ll of FIG. 2, and showing the piston and cylinder arrangement, and the drive mechanism for reciprocating the piston.

FIG. 2 is a sectional view taken through line 22 of FIG. 1, and showing the pumping head and the two elastomeric tubes in combination with various perforated sleeves which form limit surfaces for the tubes.

FIG. 3 is a sectional view taken through line 33 of FIG. 2, and showing another view of the piston and cylinder arrangement, and the drive mechanism for reciprocating the piston.

FIG. 4 is a sectional view taken through line 44 of FIG. 3 and showing how the crosshead of the drive mechanism is confined within the pump.

FIG. 5 is a view taken through line 55 of FIG. 1, and showing the counter readout.

FIG. 6 is a partial sectional view through a modified form of the pumping head of the present invention, similar to the right hand portion of FIG. 2, and specifically illustrating the two elastomeric tubes in a different combination with perforated sleeves.

FIG. 7 is a partial sectional view of still another embodiment of pumping head, similar to FIG. 6.

FIG. 8 is a partial sectional view of a further embodiment of the pumping head of the present invention in which the two elastomeric tubes are concentrically arranged in combination with various perforated sleeves which form limit surfaces for the tubes.

FIG. 9 is a partial sectional view of the embodiment shown in FIG. 8, but showing the two elastomeric tubes in a different combination with perforated sleeves.

FIG. 10 is a partial sectional view of the embodiment shown in FIG. 8, but showing the two elastomeric tubes in a different combination with perforated sleeves.

FIG. 11 shows a side view of an expanded elastomeric tube.

FIG. 12 is a sectional view taken through line 12-12 of FIG. 11.

FIG. 13 is a side view of a compressed elastomeric tube.

FIG. 14 is a sectional view taken through line l414 of FIG. 13.

FIG. 15 is a sectional view taken through line l515 of FIG. 13.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIGS. 1 through 4, it can be seen that the metering pump 10 is driven by a conventional electric motor 12, the latter being mounted to the pump frame 14. The motor 12 is coupled by suitable means 16 to worm 18, the latter being an element of the overall drive mechanism 20 which is mounted within the reservoir 22 defined within the pump housing of 24. The drive mechanism 20 is utilized to convert the rotary motion of the motor 12 into reciprocating motion at the proper pumping speed. As can be seen, the worm 18 is mounted in the housing 24 on suitable tapered roller bearings 26.

As worm 18 rotates, it drives a worm gear 28 with which it meshes. Because the latter is mounted on shaft 30 by means of a key 32, the shaft is caused to rotate on tapered roller bearings 34. As the shaft 30 rotates, it drives a rotary member 36 which is eccentrically mounted on said shaft 30 by means of the key 32. Both the gear 28 and member 36 are locked in predetermined positions along the axis of shaft 30 by means of sleeve sections 38, 40, and 42, section 40 having a slot formed therein to permit the key 32 to extend therethrough.

Surrounding member 36 in rotatable relationship thereto, is sliding block 42, and enclosing the latter is a crosshead 44. Crosshead 44 is supported within hous ing 24 by bearing support means 46, that define a bore 47, the bore confining the movement of the crosshead to a reciprocating movement. Because member 36 is eccentrically mounted on shaft 30, the block 42 is confined by its engagement in slots 48 formed in the crosshead 44, the movement of the block 42 surrounding member 36 will be an oscillating movement. This oscillating movement of block 42 is converted into a reciprocating movement by the crosshead 44, the latter being confined to move within bore 47 as described above.

In order to transmit the reciprocating motion of crosshead 44 to piston 50, the latter is connected to the crosshead by a connecting pin 52, the pin being accessible from the exterior of pump 10 when the vent cap 53 is removed. The cap 53 is located in line with the path of the pin 52, and when it is desired to disconnect the crosshead 44 from the piston 50, the cap is removed and the coupling 16 is rotated until the pin is accessible by means of a suitable wrench inserted through the opening into which the cap was screwed.

As illustrated in phantom, in the right hand portion of FIG. 1, the crosshead 44 may be employed to drive a rair of pistons, and correspondingly, two separate pumping heads.

The piston 50 reciprocates within a cylinder defined by housing 24, which cylinder includes a sleeve 54 which surrounds the piston in sliding relationship thereto. It is noted that piston 50 has a plurality of ports or passageways 56 in the form of end milled undercuts on the perimeter of the piston. During reciprocation of piston 50, passageways 56 periodically communicate with reservoir 22, resulting in driving fluid passing into and out of the displacement chamber 58 during alternating strokes of piston 50, the reservoir 22 containing a supply of driving fluid. To vary the degree to which the displacement chamber 58 is placed in communication with reservoir 22 during the reciprocation of piston 50, sleeve 54 is adjustably mounted so that it can be moved with respect to the piston in a direction parallel to the direction of reciprocation thereof. It is noted that the sleeve 54 contains a circumferential groove 60 which communicates with openings 61 formed on opposite sides of the sleeve.

To adjust the position of sleeve 54 with respect to piston 50, a handwheel 62 has a shaft 63 which is threadably connected to sleeve 54 as indicated at 64, FIG. 1, the shaft being rotably confined within pump housing 24. Rotating handwheel 62 consequently causes sleeve 54 to move toward or away from crosshead 44, depending upon the direction of rotation. A digital counter 66 (commercially available from Veeder Root Corporation of Hartford, Conn.) has a gear 68 which meshes with gear 70 on the handwheel shaft 63, the counter reading from O to percent of pump capacity, a universal readout that does not require conversion to ume of driving fluid confined in chamber, 58 between other units. Thus, the longitudinal position of sleeve 54 the piston 50 and tube 74 will be displaced, thus exwith respect to piston 50 determines the effective hypanding the tube. The tube 74 will expand until it is utdraulic displacement of the pump 10. Shaft 63 rotates limately restrained by an annular limit surface 78 which within cylinder end closure 65, the latter being secured 5 is defined by a perforated sleeve 80 which surrounds in place by bolts 67. An O-ring seal 69 is mounted bethe tube. The contoured limit surface 78 is designed so tween the shaft 63 and pump housing 24. as to support the expanded tube 74 within its elastic When sleeve 54 is in the position which is farthest limit. As used herein, annular limit surface means from crosshead 44, there is zero effective hydraulic disthat surface which is defined by a perforated sleeve, placement. In this position, the circumferential groove 10 and which allows an elastomeric tube to expand or con- 60 communicates with passageways 56 throughout the tract freely, but which will keep the tube from being reciprocation of piston 50, thus driving fluid is alterdistorted beyond its elastic limit. In other words, the nately withdrawn from and forced into the sump or reselastomeric tube will not be forced to follow a shape ervoir 22 without driving force being applied to the other than the one which is freely formed as it is disdriving fluid in the displacement chamber 58. As the torted by the driving fluid. The term annular limit sursleeve 54 is moved closer to crosshead 44, passageways face also applies to one defined by a perforated sleeve 56 will eventually override circumferential groove 60 which stops the tube in its nondistorted or original posiduring the discharge stroke of the piston 50 (leftward tion. i as viewed in FIG. 1), resulting in an effective hydraulic The latent energy imparted to tube 74 during its exdisplacement for the remainder of the discharge stroke, pansion during the discharge stroke of piston 50, is and the application of driving force to the driving fluid given up on the return or suction stroke of the piston. in chamber 58. The maximum hydraulic displacement As the tube 74 elastically returns to predistorted posiis achieved when sleeve 54 is in the position which is tion, it maintains a pressure in the displacement chamclosest to crosshead 44. Even in this latter position, ber 58 until passageways 56 once again communicate however, there is still a very slight communication be-- with the reservoir 22 which is connected to the atmotween passageways 56 and circumferential groove 60 sphere. The pressure maintained in the displacement to assure expulsion of air from displacement chamber chamber 58 keeps the driving fluid above its vapor 58; there is about a 0.125 inch overlap between the pressure, and also keeps dissolved gases in solution that passageways 56 and groove 60. The degree to which would otherwise break out of solution and subtract passageways 56 communicate with reservoir 22 is profrom the volumetric intake, and subsequently the voluportional to the position of sleeve 54 within the pump metric efficiency of the pump. housing 24. The generous porting provided by passage- A sleeve 82 is also mounted or arranged within the ways 56 reduces the pressure required to expel oil from tube 74, this sleeve defining an annular limit surface the displacement chamber during reciprocation, consewhich stops the tube in its original or nondistorted posiquently permitting higher pumping speeds since the tion, and which prevents the tube from moving beyond fluid flow velocities are easily kept within allowable its elastic limit. By mounting sleeve 82 within the hylimits. draulic tube 74, the pump 10 can continue to operate It is noted that sleeve 54 is hydraulically balanced even if the process tube 94, to be discussed in detail and requires little more force for adjustment than is hereinafter, ruptures during operation of the pump. If necessary to overcome the frictional resistance of the sleeve 82 were not provided, the hydraulic tube 74 O-ring seals located on the inner and outer diamemight be totally collapsed on the suction stroke of the ters of the sleeve. Each end of the sleeve 54 is subjected piston 50 to such an extent that damage and eventual to atmospheric pressure which thus permits the sleeve rupture might occur. Sleeve 82 also serves to assist in to be easily adjusted regardless of whether the piston keeping the ends of tube 74 secured in place within the 50 is on a suction or discharge stroke. pump.

Associated with the piston 50, and the above dis- As driving fluid is, displaced within displacement cussed drive mechanism, is a pumping head, designated chamber 58 during the discharge stroke of piston 50,

generally 73. The pumping head 73, in the illustrated the pressure of the driving fluid will rise. A hydraulic embodiment, is formed as an integral unit of the entire relief valve 84 is provided which protects the pump 10 pump assembly, sections thereof serving to define a 50 from overpressure conditions, possibly caused by an portion of the displacement chamber 58. Generally, as accidental blockage of the pump discharge, etc. Relief will be detailed more fully hereinafter, the pumping -valve 84 will permit the driving fluid to be passed to the head 73 includes an elastomeric hydraulic tube 74, a reservoir 22 in the event a predetermined pressure is chamber 88 for intermediate fluid, and a flexible proreached during the discharge stroke of piston 50. A cess tube 94 providing a pumping chamber 100. It is to clear plastic window or bubble 86 is provided above the be understood that the pumping head 73 may be relief valve 84 in order to permit visual inspection of formed as a separable unit, with means being provided the valve operation to determine when driving fluid is for operable connection of the displacement chamber being passed to the reservoir. of the pumping head, with that of adisplacement piston As tube 74 is expanded on the discharge stroke of and drive arrangement. Further, while the tubes 74 and piston 50, it causes displacement of an intermediate 94, as illustrated, are elastomeric, they may be condriving fluid which is contained within an intermediate structed of any suitable flexible material. chamber 88, this latter chamber being partially defined The displacement chamber 58 which confines a volby the outer surface 90 of tube 74, and the outer surume of driving fluid during the discharge stroke of pisface 92 of an elastomeric process tube 94. The diston 50, is partially defined by an elastomeric hudraulic placement of the intermediate fluid compresses process tube 74, in particular by the inner surface 76 of the tube 94, causing a discharge displacement from the tube. During the discharge stroke of piston 50, a volpump 10. Surrounding tube 94, is a perforated sleeve 96 which defines an annular limit surface 98. Annular limit surface 98 also serves to maintain tube 94 within its elastic limit. As with limit surface 78, limit surface 98 is coincident with the contoured shape which is freely assumed by the distorted tube 94 as a result of the pressure of the driving fluid and while the tube is within its elastic limit. Therefore, tube 94 cannot be forced to assume a shape other than one freely formed as it is compressed by the intermediate driving fluid. This results in an elastic distortion without the stress concentrations caused by stretching the tubes irregularly beyond its normal freely distorted shape.

It is noted that each of the tubes 74 and 94 have their ends secured within the pump 10 so as to permit distortion of the central portion of each tube. Each of the tubes alternates between a first configuration and a second configuration during the reciprocation of piston 50. The driving fluid confined within displacement chamber 58 causes the tube 74 to assume its alternate configurations. while the intermediate driving fluid within intermediate chamber 88 causes tube 94 to assume its alternating configurations during the operation of the pump. The alternating configurations assumed by tube 94 results in a process fluid being pumped through the pumping chamber 100, the latter being partially defined by the inner surface 102 of the tubes 94, and an inlet valve 104, and an outlet valve 106.

Tube 94, when operating with a suction lift, compresses elastically on the discharge stroke of piston 50, and cannot be compressed beyond the volume displacement extension limit of the hydraulic tube 74. Therefore, tube 94 cannot be over compressed to an extent such that the walls of the tube come into contact with each other.

Referring to FIGS. 11 through 15, the shapes assumed by tubes 74 and 94 during distortion (expansion or contraction) are shown. FIGS. 11 and 12 show the configuration assumed by a tube when it is expanded. F165. 13 through 15 show the configuration assumed by a tube when it is contracted. It is noted that the perimeter of an expanded tube is greater than when the tube is in its nondistorted position, while the perimeter of a compressed tube is the same or substantially the same as when the tube is in its nondistorted position. Thus, more energy is required to expand the tube 74 than is required to compress the tube 94. Both tube 74 and tube 94 aid in the suction lift capability of pump 10. The energy imparted to tube 74 to expand the same, and the energy imparted to tube 94 to compress the same, during the discharge stroke of piston 50, is given up on the return stroke of the piston. The additive aid given to the suction lift capability of the pump 10 is substantially greater for tube 74, however, than for tube 94, because as stated above, more energy is required to expand tube 74 than is required to compress tube 94.

The ability of the combined hydraulic tube 74 and process tube 94 to aid in the suction lift capability of the pump 10 is dependent upon the physical characteristics of the flexible material from which each tube is manufactured. Because tube 74 is the most highly stressed and consequently the greatest aid when pumping with a suction lift, its physical characteristics are most important. Fortunately, tube 94 is isolated from the process fluid being pumped through pumping chamber 100, and consequently does not come into contact with the process fluid.

In a suction lift application, the elastomeric material from which the tube 74 is constructed. is selected for its high modulus of elasticity. Therefore, as previously explained on the suction stroke of piston 50, hydraulic tube 74 maintains ahydraulic pressure in the displacement chamber 58 until the tube 74 returns to its predisplaced position. The suction lift capability of pump 10, however, is not dependent solely upon the elastic characteristics of the tubes 74 and 94. The suction lift capability of the pump is also aided by the suction stroke of the piston 50 which creates a pressure which is less than atmospheric in the displacement chamber 58, thus aiding in the total suction lift potential of the pump 10.

Because process tube 94 is almost always coming into contact with process fluids that are corrosive or abrasive, the selection of the elastomeric material for the process tube is based on its resistance to these fluids. The best materials for corrosion resistance do not necessarily have the physical properties required for the hydraulic tube 74. A pump utilizing the present double tube arrangement, has an excellent suction lift capability which is aided by the characteristics of the hydraulic tube 74; in addition such a pump is resistant to abrasive or corrosive process fluid due to the characteristics of the process tube 94.

It is noted that all of the perforated sleeves disclosed in the application, have openings or holes which are symmetrically located around the sleeve, and which openings are large enough to allow the driving fluid to distort the elastomeric tubes as desired. but small enough to prevent damage to the tube due to elastic deflection of the tubes into the openings.

As a result of the alternating configurations assumed by tube 94 during the reciprocation of piston 50, process fluid enters the pumping chamber 100 via inlet line 103 and inlet valve 104, and exits the chamber via outlet valve 106. As stated above, the alternating configurations assumed by tube 94 are effected by the displacement of the intermediate driving fluid which is contained within the intermediate chamber 88. By removing plug 108, the intermediate fluid is introduced through the opening 109 into the latter chamber prior to start-up of the pump.

Inlet valve 104 is guided by four lands 110, and is stopped in an upper position by a plurality of ball stops 112, the lands and stops being sized so as to provide an adequate flow passage around the inlet valve in this upper position. When valve 104 is in this upper position, the piston 50 is on its suction stroke; during the suction stroke the energy imparted to the tube during its compression is given up, thus causing a decrease of pressure in pumping chamber 100 which is satisfied by process fluid entering the latter chamber via line 103.

As piston 50 begins its return or discharge stroke, tube 94 is compressed, thus causing the process fluid to be discharged around the outlet valve 106 and through the outlet line 114. It is noted that process fluid enters the latter line above the outlet valve 106 to assure that the flow around the outlet valve is evenly distributed so that the latter bears evenly on discharge valve spring 116. Discharge spring 116 requires a minimum dis charge pressure to lift outlet valve 106 off its seat which is equal to the minimum pressure required to displace driving fluid out of the displacement chamber 58 via r In FIG. 10, the arrangement is the same as shown in FIG. 8,except thatthe perforated sleeve 130 does not FIGS. 6 and 7 show an alternate embodiment of the pumping head of FIGS. 1 through 5, ut in Combination with different sleeve arrangements. In FIG. 6, the hydraulic tube 74 is combined with the same sleeve arrangement as shown in FIGS. 1 through 5. The process tube 94, however, is now surrounded by a perforated sleeve 1 18 which does not employ an annular limit surface as defined above. Sleeve 118 serves to assist in securing the ends of the process tube 94 in place within the pump.

In FIG. 7, the process tube is combined with the same sleeve arrangement as shown in FIGS. 1 through 5, but the hydraulic tube 74 is combined with a different sleeve arrangement. Perforated sleeve 82 is still mounted within tube 74, but surrounding the tube is a perforated sleeve 120, which similar to sleeve 118 in FIG. 6 does not employ a contoured annular limit surface as defined herein; sleeve 120 also serves to assist in securing the ends of tubes 74 in place within the pump.

FIGS. 8, 9, and 10 show a second embodiment of the invention which differs from the embodiment shown in FIGS. 1 through 7 in that the two elastomeric tubes are concentrically arranged, i.e., the hydraulic tube 74 surrounds the process tube 94. FIGS. 8, 9 and 10 differ with respect to each other only as to the sleeve arrangements. In each of the latter figures, it can be seen that driving fluid is now confined between the piston 50 and the outer surface of tube 74', rather than between the piston and the inner surface of the tube. Consequently, on the discharge stroke of piston 50, tube 74 will now be compressed rather than expanded as in the embodiment shown in FIGS. 1 through 7.

Referring to FIG. 8, it can be seen that during the discharge stroke of piston 50', driving fluid confined within the displacement chamber 58 will be displaced so as to compress the hydraulic tube 74 to the configuration shown in FIGS. 13 through 15. To control expansion and compression of tube 74, perforated sleeves 80 and 122 are provided, these sleeves defining contoured annular limit surfaces 78 and 124, respectively, which serve to control expansion and contraction of tube 74', thereby preventing damage to said tube and, to some extent, regulating or defining the limits of the pumping action.

The intermediate driving fluid contained within intermediate chamber 88 is displaced during the alternate compression and expansion of tube 74', thus producing corresponding contraction and expansion of the process tube 94. Tube 94 cannot be over expanded because of the annular limit surface 126 which is contoured to define or limit maximum expansion thereof. As tube 94' is compressed, process fluid is displaced from pumping chamber 100 around outlet valve 106'. On the suction stroke of piston 50', tubes 74' and 94' are expanded, consequently causing process fluid to enter the pumping chamber 100' around inlet valve 104. When the latter valve is in the position shown in FIG. 8, it is guided by four lands 110 and stopped by ball stops 112', these lands and stops being sized so as to provide adequate flow passages around the valve.

In FIG. 9, the arangement is the same as shown in FIG. 8, except that the perforated sleeve 128 does not define a contoured annular limit surface surrounding the tube 94'.

' define a contoured annular limit surface surrounding the tube 74.

It is noted that in the embodiment shown in FIGS. 8, 9 and 10, the hydraulic tube 74 does not aid substantially in the suction lift capability of the pump, because the tube is now compressed rather than expanded as in the embodiments shown in FIGS. 1 through 7. Consequently, because much less energy is required to compress the tube than expand it, much less energy is also released by the tube during the suction stroke of piston 50?.

We claim:

1. An improved pump which comprises: a housing having a cylinder therein and including a reservoir for operating fluid; a piston slidably mounted within said cylinder and providing a piston chamber; port means operatively connecting said piston chamber with said reservoir; drive means for effecting reciprocating movement of the piston whereby displacement of operating fluid may be effected; pumping head means operatively connected with said piston chamber and including flexible means and, which flexible means serves to define a portion of a chamber means for confining a volume of driving fluid between said piston and said flexible means, said flexible means being adapted to alternate between a first configuration and a second configuration during displacement of operating fluid in said chamber means; the improvement wherein said housing includes a relatively movable sleeve which defines said cylinder, said sleeve having said port means formed therein, said port means being defined by an annular groove formed in the inner surface of said sleeve, and at least one aperture opening to the outer surface of said sleeve and being in communication with said annular groove, means mounting said sleeve for axial movement relative to said piston and said housing, such that the point in the piston stroke wherein said piston blocks said port means and exerts compressive, displacement force on the operating fluid may be varied, thereby varying the displacement of said pump, said mounting means comprising a threaded coaxial extension on said sleeve, a threaded member mounted coaxially of said sleeve and in threaded driving engagement with said threaded extension operating means extending exteriorly of said housing for effecting rotation of said threaded member, and means journalling said threaded member to saidhousing in a fixed, axial position, whereby rotation thereof will produce axial movement of said sleeve relative to said piston.

2. An improved pump according to claim 1 wherein said drive means comprises: a first member having a circular cross-section, the first member being eccentrically mounted within the housing to rotate about an axis of rotation which is normal to the cross-section; means at least partially surrounding the cross-section in sliding relationship to the firstmember; and means for causing the surrounding means to reciprocate within the housing during the rotation of the first member, and means operatively connecting the piston to the surrounding means so as to cause the piston to reciprocate during the rotation of the first member.

3. An improved pump according to claim 2, wherein the surrounding means comprises:

a. a second member disposed in sliding relationship to the first member; and

b. a crosshead, the crosshead being connected to the piston and having means for holding the second member in a position along the axis of rotation so as to be driven by the first member.

4. An improved pump according to claim 1 wherein said pumping head means comprises: a flexible first tube having inner and outer surfaces, said first tube being mounted such that the central portion thereof is free to distort; a flexible second tube having inner and outer surfaces, said second tubebeing mounted such at the central portion thereof is free to distort under fluid pressure; means, including one of said surfaces of the first tube and the outer surface of said second tube, de-

second configurations. 

1. An improved pump which comprises: a housing having a cylinder therein and including a reservoir for operating fluid; a piston slidably mounted within said cylinder and providing a piston chamber; port means operatively connecting said piston chamber with said reservoir; drive means for effecting reciprocating movement of the piston whereby displacement of operating fluid may be effected; pumping head means operatively connected with said piston chamber and including flexible means and, which flexible means serves to define a portion of a chamber means for confining a volume of driving fluid between said piston and said flexible means, said flexible means being adapted to alternate between a first configuration and a second configuration during displacement of operating fluid in said chamber means; the improvement wherein said housing includes a relatively movable sleeve which defines said cylinder, said sleeve having said port means formed therein, said port means being defined by an annular groove formed in the inner surface of said sleeve, and at least one aperture opening to the outer surface of said sleeve and being in communication with said annular groove, means mounting said sleeve for axial movement relative to said piston and said housing, such that the point in the piston stroke wherein said piston blocks said port means and exerts compressive, displacement force on the operating fluid may be varied, thereby varying the displacement of said pump, said mounting means comprising a threaded coaxial extension on said sleeve, a threaded member mounted coaxially of said sleeve and in threaded driving engagement with said threaded extension operating means extending exteriorly of said housing for effecting rotation of said threaded member, and means journalling said threaded member to said housing in a fixed, axial position, whereby rotation thereof will produce axial movement of said sleeve relative to said piston.
 2. An improved pump according to claim 1 wherein said drive means comprises: a first member having a circular cross-section, the first member being eccentrically mounted within the housing to rotate about an axis of rotation which is normal to the cross-section; means at least partially surrounding the cross-section in sliding relationship to the first member; and means for causing the surrounding means to reciprocate within the housing during the rotation of the first member, and means operatively connecting the piston to the surrounding means so as to cause the piston to reciprocate during the rotation of the first member.
 3. An improved pump according to claim 2, wherein the surrounding means comprises: a. a second member disposed in sliding relationship to the first member; and b. a crosshead, the crosshead being connected to the piston and having means for holding the second member in a position along the axis of rotation so as to be driven by the first member.
 4. An improved pump according to claim 1 wherein said pumping head means comprises: a flexible first tube having inner and outer surfaces, said first tube being mounted such that the central portion thereof is free to distort; a flexible second tube having inner and outer surfaces, said second tube being mounted such at the central portion thereof is free to distort under fluid pressure; means, including one of said surfaces of the first tube and the outer surface of said second tube, defining an intermediate chamber adapted to contain a volume of intermediate fluid, such that distortion of said first tube will produce distortion of said second tube, and wherein the inner surface of said second tube provides the pumping chamber; and means including the other surface of said first tube defining a chamber in communication with said piston chamber such that operating fluid may be placed in communication with said other surface and the displacement of said operating fluid by said pump will cause said first tube and correspondingly said second tube to assume said first and second configurations. 